I welcome collaboration from everyone (including corporations).

With permissive license, corporations are allowed publish a modified version of the software while restricting their code modifications from release to the community. That is not collaboration. Permissive license benefits corporations more than the community.

corporations are a major (majority) source of Open Source

Which is why they choose permissive licenses for their projects. They receive code contributions from the community and then suddenly: rugpull! Starting from next version the software will be proprietary. The community contributors are of course having pikachu face when they realize the corporations are legally permitted to take the fruit of their labor from them because their contributions are under permissive license.

Nothing have been lost.

My time and effort has been lost. The fruit of my labor has been lost. When i contribute or make to a Free Software project, i wish for it to benefit the community the most. If corporations want to release a software based on modified version of my code, I want a guarantee that the modified code to be available to the community too. The corporations benefit from my labor, but the community receives the company’s modified code too. That’s collaboration. Copyleft licenses such as GPL guarantees this.

Of course, such guarantee is considered “restriction” if one never intends the community to be the primary beneficiary in the first place.

When I release code as Open Source, I am providing unpaid labour to everyone.

With permissive license your free labor benefits corporations the most. Corporations that take things and enshittify them and do not give back to the community, all the while they get rich. Your choice your prerogative.

Permissive license means that whoever (say a corporation) modifies some code and release a software from it, they are not obligated to release the modified code under the same license. Which means they can use Open Source software to make proprietary software, make money off it, and the community receives nothing back for their labor.

GPL forbids this. With GPL anyone can still modifes the code and release a software from it. But it obligates that the modified code must be released as GPL too. So GPL guarantees that the community benefits.

The act of choosing a license political one. Are you willing to provide unpaid labor for corporations? Or do you want your code to benefit communities?